Summary
Students will explore the relationship between the fossil record and the digestive system using coprolites (i.e., fossilized poop) as a phenomenon. Students will explain what coprolites can tell us about the diet of the organisms they came from by investigating the chemical and physical processes of digestion and connecting these to prior knowledge of fossil formation. Further exploration of scientific data behind the fossil phenomenon helps students draw conclusions about ecosystem-level interactions.
Essential Question(s)
How can we use fossils to learn about ancient organisms' diets and ecosystems?
Snapshot
Engage
Students view museum images of fossilized wild dog coprolites and construct initial explanations for how it’s possible for us to know how the dogs hunted based only on those fossils.
Explore
Students investigate the process of digestion using a physical model.
Explain
As a class, students discuss how waste products from digestion can provide information about an organism's diet and explain why this evidence is rare in the fossil record.
Extend
Using data from the scientific paper about the wild dog coprolites, students match the scientists' conclusions about the dogs' ecosystem to evidence that supports these claims. In addition, students provide scientific reasoning to justify the way they matched up the scientists' evidence and conclusions.
Evaluate
Students create a model to explain how digestion can produce the type of evidence found in the wild dog coprolites and why that evidence is useful for understanding ancient ecosystems.
Materials
Lesson Slides (attached)
CER Explanations handout (attached; one per student; print on both sides)
Digestion Model Student Guide (attached; one per student)
Digestion Model Teacher Guide (attached)
Model Observation Notes handout (attached; one per student)
Unveiling the Digestive System handout (attached; one per student; print on both sides)
“Bone-crushing” Dogs Articles (linked; one per student)
Evidence and Conclusions handout (attached; one per student)
Digestive System Model handout (attached; one per student)
Below are the materials needed for the investigation (amounts vary):
Scissors (one pair per small group)
Gallon plastic bags (one per small group)
Metal trays (one per small group)
Plates/trays/dishes (one per small group)
Small and large plastic cups (one small and one large per small group)
Paper cups (one per small group)
Nylon "legs" (pantyhose) (one pair per small group)
Food samples (seeds, popcorn kernels, raisins, bananas, crackers, etc.) (one per small group)
Orange juice (one cup per small group)
Water (one cup per small group)
Engage
20 Minute(s)
Using the attached Lesson Slides displaying slide 2 to introduce the lesson. Students should have prior knowledge of how fossils form and how we use the fossil record to understand the past. Use slides 3-4 to review this information. Display slide 5 to introduce the essential question: How can we use fossils to learn about ancient organisms' diets and ecosystems?
Move on to slide 6 to introduce the lesson objectives to the students.
Display slide 7. As a formative assessment, ask students to explain what they know about poop. Use the Collective Brain Dump strategy to structure this conversation. Arrange students into small groups and encourage them to collaborate with their groups to share knowledge. When groups seem to be done sharing with one another, have each group share their knowledge with the whole class. As groups share, list their items on the board to create a whole-class product. Using the whole-class list, you can guide the lesson to address misconceptions and gaps in knowledge. Use the questions on the slide to help generate interesting discussion on this topic:
What is poop?
Why do we poop?
Where does poop come from?
Display slide 8. Show students images of the coprolites from the Natural History Museum of LA County. Tell them that scientists were able to figure out how the "bone-crushing" dogs hunted based on these fossils.
Display slide 9. Give students the CER Explanations handout. Ask them to write an initial explanation for how it was possible for scientists to draw that conclusion. After they are done writing, have students discuss their explanation with their neighbor.
Explore
30 Minute(s)
Transition to slides 10 and 11 to provide class-specific instructions for how to acquire the materials and complete the model.
Pass out the Digestion Model Student Guide for conducting the digestion model simulation. Use the Digestion Model Teacher Guide to help set up the parts of the model and support student understanding. Having students work in pairs is useful for this activity if the class is sufficiently small. Depending on class size and student responsibility, it may be helpful to have the entire class go through the activity at the same pace.
Display slide 12. Pass out the Model Observation Notes handout. As students explore the model, they should record observations of what they see happening at each phase such as:
What the food materials look like before and after they enter each phase.
Any "indigestible" materials in their food
Have students clean up their lab stations, using slide 13 for any class-specific instructions.
Explain
25 Minute(s)
Pass out Unveiling The Digestive System handout. Display slide 14. As a class, ask students to describe what happened in each step of the model. Display slide 15. For each step, ask them to describe what part of their body the process is occurring in. (What organ does this part of the model represent? What process in digestion does this part of the model represent?) Display slide 16. Next, ask students where they think chemical reactions are happening in the system. Have them justify their claims based on prior knowledge and what they observed in the model.
After the group discussion, provide students a formal explanation of the digestive system using slides 17-19. While it's important to cover the entire system, focus more heavily on the structures and processes students misunderstood or left out during the conversation. See the teacher’s note below for more details about the structures.
If they already know part of the content, a brief overview is all that is necessary for those details. Include in the discussion:
organs
enzymes (students don't need to remember the specific names, just the purpose)
processes
places where chemical reactions occur
Display slide 20. Once students have a complete understanding of digestive processes, return to their observations from the Explore. Ask them to describe what they were able to identify in the "waste" products of the models. Help students connect this to their understanding of how fossils form. Some guiding questions to help facilitate this include:
What types of materials are most/least likely to fossilize?
Why are coprolites rare?
When poop does fossilize, what sort of materials might be found inside? Why?
To further discussion, unhide slide 21, synthesizing content can be facilitated through student-generated questions. Student questions may include:
Why can't we eat our poop?
Why do some animals eat their poop?
Display slide 22. Have students brainstorm the types of conclusions they might be able to draw about an animal based on what they might find in its poop (e.g., whole seeds would tell us that animals can't digest that food).
Extend
30 Minute(s)
Display slide 23. Remind students that scientists figured out how the "bone-crushing" dogs hunted based on their coprolites. Ask them to revise their explanation on the CER Explanations handout for how this is possible using what they now understand about digestion.
Display slide 24. Introduce to students the Jigsaw strategy. Students read a section about the scientific research on the "bone-crushing" dogs and teach their group about their section. Divide the article What can ancient dog poop reveal about an ecosystem? into four even sections. Group students into groups of four. Give students five minutes to read and discuss what they read.
Discuss the article as a class to help students determine why bones and other materials are left behind during digestion (e.g., lack of necessary enzymes, too dense for the body to break down physically, etc.).
Display slide 25. Provide students with the Evidence and Conclusions handout. It contains the evidence scientists found within the coprolites and the specific things they concluded about the "bone-crushing" dogs' ecosystem. Ask students to match the evidence and conclusions by deciding what evidence supports each conclusion and explain why using what they understand about digestion and fossils. Note that pieces of evidence can be used to support more than one conclusion and conclusions may be supported by more than one piece of evidence. Display slide 26. After students complete the task, have them compare their answers and reasoning with a partner. They should discuss why their ideas may be different by using the evidence and their learning so far.
Students may generate questions which provide an opportunity for a discussion connecting previous knowledge and the content learned during the lesson. The following questions may be particularly useful for reinforcing conceptual understanding of both the process of fossilization and chemical reactions during digestion, respectively:
Why is poop less likely to fossilize?
Why do poop and gas smell?
Evaluate
15 Minute(s)
Display slide 27. Have students explain how the process of digestion left bone fragments in the coprolites of "bone-crushing" dogs. Provide the students with the Digestive System Model handout for them to use as part of their explanation.
In addition, students should revise their Engage/Extend explanation one more time to describe why scientists can use materials found in coprolites to understand ancient ecosystems. They should structure their final explanation as a CER, using evidence from the lesson to support their claim.
Display slide 28. Use the Muddiest Point strategy to close the lesson. Ask the students "What is your muddiest point about how we can use fossils to learn about ancient organisms' diets and ecosystems?" Use student responses to address any remaining misconceptions or wonderings.
Resources
Coprolites & Dinosaur Poop. (n.d.). Explore the Fascinating World of Coprolites & Dinosaur Poop. Poozeum. https://poozeum.com/coprolites
Dinosaur Poop Part 1: Who Dung It? (2018, March 15). Tumble. http://www.sciencepodcastforkids.com/single-post/2018/03/09/Dinosaur-Poop-Part-1-Who-Dung-It
Extinct Doggos' Bone-Crushing Diet Preserved in Fossil Poop. (n.d.). Live Science. https:///62666-extinct-doggos-munched-bones.html
Fritts-Penniman, A. What can ancient dog poop reveal about an ecosystem? (2018, July 5). Massive Science. https://massivesci.com/articles/ancient-dog-fossils-bones/
K20 Center. (n.d.). Claim, evidence, reasoning (CER). Strategies. https://learn.k20center.ou.edu/strategy/156
K20 Center. (n.d.). Collective brain dump. Strategies. https://learn.k20center.ou.edu/strategy/111
K20 Center. (n.d.). Muddiest point. Strategies. https://learn.k20center.ou.edu/strategy/109
Lesson Idea: Digestive System Experiment: Reach Out Cpd. (2014). YouTube. https://www.youtube.com/watch?v=7av19YhNkhE
The Digestive System. (2012). YouTube. http://youtu.be/_QYwscALNng
The Proof Is in the Pooping. (n.d.). National History Museum. https://nhm.org/stories/proof-pooping
Wang, X., White, S. C., Balisi, M., Biewer, J., Sankey, J., Garber, D., & Tseng, J. First bone-cracking dog coprolites provide new insight into bone consumption in Borophagus and their unique ecological niche. (2018, May 22). eLife. https://elifesciences.org/articles/34773